No they don't like to talk about it because it is not their client. Size in terms of usage will be roughly similar to O2 so in the region of 20,000 per week when it is fully rolled out.
They have though recently renotiated the Bt contract in their favour. The revenue split is now roughly 70/30 as opposed to 60/40. There are also future trigger points built in as volume rises so eventually I would imagine that it would end up at around 90/10. Gross margins have as a result improved.
What is of far greater importance though is the major retail banks signed up. As they spread through the various banks dividion by division I would expect some large stepped increases in usuage.